026 build running a bit lackluster

[NateSaw]

Two port transfers are lazy. Open them sooner to give them a head start.

Not to mention I already further lazied the crank pressure with my hogged lowers.

 

[NateSaw]

I usually don't chime in. So many ways to skin a cat....

I'm honored. I trolled this site before joining. I feel like I have some of the pick of the litter throwing me hints! I dig! (or grind lol)

 

[Mastermind]

Not to mention I already further lazied the crank pressure with my hogged lowers.

I wasn't going to mention that.

 

[NateSaw]

I wasn't going to mention that.

Don't be shy. I started this thread because I knew I didn't know lol. All my years of wrenching, 2 strokes are an art for sure. I've merely dabbled. I'm hoping to gain the how's and why's here. I'm not looking to just do as others do... So I like the hints and nudging. Gimme enough leash to hang myself?

 

[Mastermind]

Don't be shy. I started this thread because I knew I didn't know lol. All my years of wrenching, 2 strokes are an art for sure. I've merely dabbled. I'm hoping to gain the how's and why's here. I'm not looking to just do as others do... So I like the hints and nudging. Gimme enough leash to hang myself?

Like I said. There are too many ways to skin a cat for me to say that anything is "wrong".

 

[huskihl]

Like I said. There are too many ways to skin a cat for me to say that anything is "wrong".

It’s technically not wrong. Just need to figure out a way to get it to turn 20k and those lowers will be

 

[Mastermind]

It’s technically not wrong. Just need to figure out a way to get it to turn 20k and those lowers will be

Yep. Yep. Yeppers.

 

[NateSaw]

It’s technically not wrong. Just need to figure out a way to get it to turn 20k and those lowers will be

Idk if this unbalance Chineseum crank will stay together for 20k...

 

[drf256]

024 with 44mm jug and 044 carb.


Sound like you’re getting it.

There‘s always a balance. Like Moobs said, no “wrong” way. Kevin is trying to say that your uppers/lowers might work if you used your engine for an airplane and ran it at 20k. You lowered case pressure, have too much blowdown and your uppers lack direction.

Bigger isn’t always better. Think of the transfers as a garden hose spraying water (charge) into your cylinder. Now imagine you want to wash your car. If you try to use the hose with no nozzle it flows more water overall, right? Would you wash your car with it with no nozzle (why not, it flows more water)? You‘ll use a different nozzle setting to spray a car off vs filling a bucket vs shooting a spray the furthest distance. See where I am going here?

Buy a meteor piston for your oem 44mm jug. You should be able to find an oem 44mm jug here for pretty cheap. I have used pistons here if you wanna go that way.

There is more than one way to skin a cat. For an 026, I use Treemonkey’s recipe. I cut the band flat, cut the piston dome flat, and time it at 105/120/78.

 

[NateSaw]

Too much blowdown.

 

[NateSaw]

I meant to send this. Thought it pertained to what you were suggesting.

 

[NateSaw]

024 with 44mm jug and 044 carb.
View attachment 369711

Sound like you’re getting it.

There‘s always a balance. Like Moobs said, no “wrong” way. Kevin is trying to say that your uppers/lowers might work if you used your engine for an airplane and ran it at 20k. You lowered case pressure, have too much blowdown and your uppers lack direction.

Bigger isn’t always better. Think of the transfers as a garden hose spraying water (charge) into your cylinder. Now imagine you want to wash your car. If you try to use the hose with no nozzle it flows more water overall, right? Would you wash your car with it with no nozzle (why not, it flows more water)? You‘ll use a different nozzle setting to spray a car off vs filling a bucket vs shooting a spray the furthest distance. See where I am going here?

Buy a meteor piston for your oem 44mm jug. You should be able to find an oem 44mm jug here for pretty cheap. I have used pistons here if you wanna go that way.

There is more than one way to skin a cat. For an 026, I use Treemonkey’s recipe. I cut the band flat, cut the piston dome flat, and time it at 105/120/78.

I'm totally drinking what you're pouring. It's about velocity versus volume. I have a stock jug, but no lathe... I can use my guerrilla methods to lower the jug / sand in the squish to the piston... The only way I'll get 105 exh is to lower. I'm gonna save my Ducketts for that meteor, but I'll keep playing with this heavy breathing tiawaneseum hyway till I aquire it. I just ordered the 90 degree hand peice for the foredom .
I'm excited to keep experimenting on this jug and report back to you fellers with each modifications results! What a journey! (this is fun). I could use my buddy's southbend to cut the piston flat, then use it, some sticky sandpaper, and alot of elbow to grind in the squish to match.. Then take a squish reading and do some math then deck the jug accordingly. I definitely noticed a drastic change with squish tightening. One for the better. This thing pumps up to 220psi with a .017" squish.

 

[drf256]

You don’t need more than 220 psi. The reason for cutting the squish flat is to drop the exhaust roof to 105. It sounds like you understand that.

Here’s a 44mm I did with a 25” 3/8 RS chain.

 

[NateSaw]

You don’t need more than 220 psi. The reason for cutting the squish flat is to drop the exhaust roof to 105. It sounds like you understand that.

Here’s a 44mm I did with a 25” 3/8 RS chain.

That's farkin impressive. Throttling up IN THE GD WOOD and it torqued through. Jesus man. I love it!

 

[NateSaw]

You don’t need more than 220 psi. The reason for cutting the squish flat is to drop the exhaust roof to 105. It sounds like you understand that.

Here’s a 44mm I did with a 25” 3/8 RS chain.

A. Graham Bell had some neat things to say about squish, and the positive effect making it flat and tight has on the flame front. How it contains the combustion in the center of the piston and eliminates detonation... (being an old Saab turbo guy, I've learned alot about detonation and controlling flame front. It costs more to melt down 4 pistons... Hey, at least I had each cylinder even lol)

 

[Mastermind]

View attachment 369712
I meant to send this. Thought it pertained to what you were suggesting.

Those books are not going to help much on saw building. They relate to longer stroke engines with bigger carbs, and tuned pipes.

220psi

Not needed. 180 or so is enough.

 

[NateSaw]

Those books are not going to help much on saw building. They relate to longer stroke engines with bigger carbs, and tuned pipes.

Not needed. 180 or so is enough.

I might be being generous. I'm using an automotive compression tester, so I know it takes a while to fill the hose, but I mean it takes a while to pump it up to that. Should I go with the fist pop, or 5, or till the gauge stops?

 

[Mastermind]

I might be being generous. I'm using an automotive compression tester, so I know it takes a while to fill the hose, but I mean it takes a while to pump it up to that. Should I go with the fist pop, or 5, or till the gauge stops?

Till it stops

 

[NateSaw]

Your dogs could be part of the reason, depending on how long they are. The 026 isn’t known for having lots of torque and that would become more noticeable with those on there. The other thing that isn’t helping you is your lower transfers opened up that much.

 

[NateSaw]

@huskihl , I have to test this, but what you were saying is spot on... The more I looked at the physics of those dogs, the more clear it was to me that the moment the chain pulled in that bottom dog, the harder it tried to pivot the saw down into the woods. So I raised that dog and shortened them all. Really, I'd be wise to, as you pointed out, start the chain in the wood till the bar is deep enough to engage the center dog, then let it pull in. The fulcrum of the center dog is now slightly above the chain curf. That lower dog will be useless until/if I get more power out of this thing. I'd have raised it further, but alas, the chain catcher is running out of room lol.